Permafrost structural support with heat pipe stabilization

ABSTRACT

Structural support assembly for use in arctic and subarctic (permafrost) areas or in any areas where the upper ground layer is subject to a severe annual freeze-thaw cycle, including the cooperative combination of a support structure and a heat pipe element installed in generally frozen soil. The heat pipe is of a suitably complementary configuration and/or disposition with respect to the support structure to provide appropriate stabilization of the surrounding frozen soil. In one embodiment, the heat pipe element is disposed externally of the support structure and, in another embodiment, it is disposed internally of (and integrally combined with) such structure. The external embodiment further includes one version employing a linear (straight) heat pipe element and another version employing an angular (helical) element.

United States Patent 3 1191 Waters l PERMAFROST STRUCTURAL SUPPORT WITHHEAT PIPE STABILIZATION [75] Inventor: Elmer Dale Waters, Richland,

Wash.

[73] Assignee: McDonnell Douglas Corporation,

Santa Monica, Calif.

[ Notice: The portion of the term of this patent subsequent to Jan. 29,1990, has been disclaimed.

[22] Filed: Mar. 12, 1973 [21] Appl. No.: 339,769

Related US. Application Data [62] Division of Ser. No. 174,687, Aug, 25,1971, Pat. No.

1111 I 3,840,068 145 *Oct. 8, 1974 3,472,314 10/1969 Balch ..l65/45XPrimary Examiner-Albert W. Davis, Jr. Attorney, Agent, or FirmD. N. Jeu;Walter J. Jason; Donald L. Royer 5 7] ABSTRACT Structural supportassembly for use in arctic and subarctic (permafrost) areas or in anyareas where the upper ground layer is subject to a severe annualfreeze-thaw cycle, including the cooperative combination of a supportstructure and a heat pipe element installed in generally frozen soil.The heat pipe is of a suitably complementary configuration and/ordisposition with respect to the support structure to provide appropriatestabilization of the surrounding frozen soil. In one embodiment, theheat pipe element is disposed externally of the support structure and,in another embodiment, it is disposed internally of (and integrallycombined with) such structure. The external embodiment further includesone version employing a linear (straight) heat pipe element and anotherversion employing an angular (helical) element.

6 Claims, 11 Drawing Figures PERMAFROST STRUCTURAL SUPPORT WITH HEATPIPE STABILIZATION This is a division, of application Ser. No. 174,687filed Aug. 25, 1971, now'U.S. Pat. No. 3,788,389.

BACKGROUND OF THE INVENTION My invention relates generally to supportstructures and, more particularly, to a novel and useful structuralsupport-assembly for use in permafrost areas or in any areas havingactive ground layers subject to a severe annual freeze-thaw cycle.

Permafrost is material which is largely frozen permanently. It isusually a mixture of soil, rock and ice although it can be anything fromsolid rock to muddy ice. In the arctic regions, permafrost may extendfrom a few feet to hundreds of feet below the surface. The permafrost isseparated from the surface by an upper layer (the tundra) and itssurfacevegetation. The upper layer or tundra serves as insulationtolimit permafrost thaw in the summer but is subject to a seasonalfreeze-thaw cycle. The permafrost thaw in the summer, however, cancreate an unstable condition for structures constructed in permafrostareas. This is, of course, more so in wet, ice-rich, permafrost areasthan in dry, stable, permafrost areas of well drained soil or rock.

There are severeproblems associated with support and stabilization ofstructures in the arctic regions where permafrost is prevalent. Alaskanrailroads, for example, require the expenditure of thousands of dollarseach year to repair soil'slippages and track roughness resulting fromthe annual freeze-thaw cycle and disturbances of the ground cover by theintrusion of man and his machines. When the-tundra is broken or removed,the permafrost loses its insulation and begins to melt and erode. Thus,tracks left by a tractor or caterpillar train can become a deep ditchand alter the surface drainage pattern over a wide area.

In cities and regions which overaly permafrost areas, a gravelinsulating technique is generally used in construction over such areas.A raised gravel pad, for example, is ordinarily employed to provide asuitable support or work area on permafrost. Foundation structuresembedded in permafrost are also. commonly surrounded completely by alayer of insulating gravel. In areas of ice-rich permafrost and/orduring a strong summer thaw, however, even the use of a relatively thickinsulating'gravel layer is inadequate to prevent some subsidence andpossibly accompanying damage of the supported structure or apparatus. Onthe other hand, instead of subsiding, support posts or poles for arcticoverhead communications and power lines have presented a particularproblem withpole jacking wherein the annual seasonal uplift due to frostheave can actually lift the poles and their anchors completely out ofthe ground. The pole jacking problem has plagued all of the utilitycompanies throughout vast areas of the subarctic regions, and ispresently considered to have no reasonable economic solution.

The US. Pat. 3,217,791 of Erwin L. Long on Means for MaintainingPermafrost Foundations patented Nov. 16, I965 discloses and claims athermo-valve foundation system including a closed tubular containerpartially filled with a low boiling point liquid, either propane orcarbon dioxide, and a layer of gravel completely surrounding its lowerportion. The thermo-valve tubular container operates during periods ofsubfreezing temperatures to absorb heat from the adjoining permafrost,to freeze the adjacent unfrozen soil and increase its strength ofadhesion to the foundation. The container itself serves as a foundationpiling or support pole which is used with a gravel layer completelysurrounding its lower portion. lt is, however, not only costly butfrequently impractical and infeasible to provide a sufficiently largeand thick insulating gravel layer entirely around and below the lowerportion of each pole to stabilize it.'Moreover, the metallic tubularcontainer of the thermo-valve system is obviously limited by practicalconsiderations in height or length and location whereas a wooden utilitypole of any substantial height or length can be economically used in anylocation.

SUMMARY OF THE INVENTION Briefly, and in general terms, my invention ispreferably accomplished by providing a structural support assembly foruse in arctic, subarctic and similar regions, including a cooperativecombination of a support structure and a heat pipe element, which can bedirectly and easily installed in generally frozen soil to provide astable support for various apparatus and structures. The heat pipeelement is of a suitably complementary configuration and/or dispositionwith respect to the support structure to provide appropriatestabilization of the surrounding frozen soil.

Where the support structure is of the form of a wooden utility pole, forexample, the heat pipe element can beof either a linear (straight)configuration or an angular (helical) one positioned adjacent to thesurface of the lower embedded portion of the pole. Both straight andhelical elements extend at least over the embedded length of theirrespective poles and protrude a predetermined distance linearly abovethe ground for heat exchange purposes. The heat pipe element broadlyincludes an elongated tubular container having a filling or charge of asuitable working fluid, and a heat exchanger (radiator) suitably coupledor integrally incorporated with the protruding upper portion of thetubular container. Means for attaching the lower embedded portion of thetubular container to the surface of the pole can be utilized wheredesired or required.

Each of the straight and helical heat pipe elements can be fabricated ina two-part assembly wherein the upper radiator section, located abovethe ground, can be readily separated and detached from the lowerembedded section. In this instance, the upper and lower heat pipesections are secured together in an overlapping joint. Heat transferbetween the two parts is facilitated by, for example, a thermal pasteused between the contiguous faces of the joined parts. While the heatremoval rate with the two-part assembly is about 12 percent less thanwith a one-part assembly, the two-part assembly permits easy replacementof a radiator that may be damaged by large animals (migrating caribou,bears, etc.) or by vandalism.

Where a wooden pole or piling cannot be used or is not desired,advantage can be taken of an integrally combined metallic supportstructure and heat pipe element assembly. This structural supportassembly includes a closed, elongated, tubular container having afilling or charge of a suitable working fluid, a helical wall finprotruding radially inwards from the internal surface of the tubularcontainer, and a heat exchanger (radiator) suit'ablycoupled orintegrally incorporated with the upper portion of the tubular container.The lower portion of the tubular container is installed directly inpermafrost to a depth such that the upper radiator portion is positionedabove the ground with its upper end located at a desired height toprovide support for associated apparatus or structure.

BRIEF DESCRIPTION OF THE DRAWINGS My invention will be more fullyunderstood, and other features and advantages thereof will becomeapparent, from the following description of certain exemplaryembodiments of the invention. The description is to be taken inconjunction with the accompanying drawings, in which:

FIG. 1 is a front elevational view, shown partially in section and insimplified form, of a test installation of different poles includingcontrol poles and those constructed according to this invention;

FIG. 2 is a front elevational view, shown partially in section and infragments, of a linear (straight) heat pipe element that is normallyattached to a wooden utility pole to stabilize the surroundingpermafrost in which it is installed;

FIG. 3 is a fragmentary sectional view of a lower part of the linearheat pipe element as taken along the line 3-3 indicated in FIG. 2;

FIG. 4 is a side elevational view of a central part of the linear heatpipe element as taken along the line 4-4 indicated in FIG. 2;

FIG. 5 is a cross sectional view of an upper part of the linear heatpipe element as taken along the line 5-5 indicated in FIG. 2;

FIG. 6 is a front elevational view, fragmentarily shown, of an angular(helical) heat pipe element that is normally attached to a woodenutility pole to stabilize the surrounding permafrost in which it isinstalled;

FIG. 7 is a side elevational view of a central part of the angular heatpipe element as taken along the line 7-7 indicated in FIG. 6;

FIG. 8 is a cross sectional view of the central part of the angular heatpipe element as taken along the line 8-8 indicated in FIG. 7;

FIG. 9 is a front elevational view, shown partially broken away, of astructural support assembly wherein a heat pipe element is constructedto serve simultaneously as the support structure;

FIG. 10 is a cross sectional view of a lower part of the supportassembly as taken along the line 10-10 indicated in FIG. 9; and

FIG. 11 is a cross sectional view of an upper part of the supportassembly as taken along the linell-ll indicated in FIG. 9.

DESCRIPTION OF THE PRESENT EMBODIMENTS In the accompanying drawings andfollowing description of certain embodiments of my invention, somespecific dimensions and types of materials are disclosed. It is to beunderstood, of course, that such dimensions and types of materials aregiven as examples only and are not intended to limit the scope of thisinvention in any manner.

FIG. 1 is a front elevational view, shown partially in section and insimplified form, of a test installation of a group of different polesincluding a regular power pole 20, a first control pole 22 set tosimulate a typical utility pole installation, a second control pole 24set with a type AM-9 chemical grout solution added to the backfillaround the pole base, a utility pole 26 with a linear heat pipe elementS attached to its lower embedded portion, and another utility pole 28with an angular heat pipe element y attached to its lower embeddedportion. The purpose of the chemical grout solution used in the backfillof the control pole 24 was to prevent water migration to the soil-poleinterface. For clarity of illustration, the heat pipe elements S and yhave been shown in considerably simplified forms. The heat pipe poles 26and 28 were installed on either side of the first control pole 22.

The four poles 22, 24, 26 and 28 were installed to evaluate themagnitude of pole jacking and the preventive effects of the heat pipeelements S and y. The poles 22, 24, 26 and 28 were installed at 30 feetspacings in order that the poles can function independently but becomparable in movement. Thermocouples 30 and a frost tube 32 wereinstalled adjacent to each pole for data comparison. A ground frost tube34 was installed between the poles 22 and 26. A 24-inch auger unit wasused to drill the installation holes and, as each hole was drilled, theground conditions were observed and noted. In general, the test groundcan be typified peaty organic silt to a depth of 2 feet and clay silt toa depth of 8 feet. The permafrost level was at a depth of approximately6 feet.

Temperatures measured by the thermocouples 30 are suitably recorded andplotted. The frost tubes 32 suspend or permit the lowering therein oftransparent containers of a (liquid) substance which gradually changesfrom a green to red color as it changes from an unfrozen to frozencondition. Thus, the frost tubes 32 provide or permit the obtaining ofvisual indications of the (unfrozen or frozen) conditions of the soiladjacent to the poles 22, 24, 26 and 28. The ground frost tube 34 wasused to provide or permit the obtaining of information on the extent ofground freezing between the poles 22 and 26.

The heat pipe elements S and y are designed especially to cause rapidfreezing of the soil around a utility pole in a radial direction alongthe full embedded pole portion so that the pole is firmly anchored fromthe ground surface into the permafrost. Water migration and frost heavedue to progressive freezing and adhesion to the pole from the groundsurface downward are thus precluded. Since soil expansion occurs in theradial direction, the vertical forces acting on the pole are minimized.Of course, unfrozen soil can accommodate the radial expansion, and thereare no appreciable detrimental forces acting to damage a heat pipeelement in the ground.

The primary measure of pole jacking is vertical movement throughout theyear. Test results showed that the existing power pole 20 and its bracerose at a relatively rapid rate. Similarly, the plots for the first andsecond control poles 22 and 24 also showed that both moved upward atcomparable rates. Of interest, the second control pole 24 with chemicalgrout added to its backfill, rose at a greater rate than any other pole.The pole 24 and stabilized soil surrounding it were apparentlybeingjacked as a single unit. The poles 26 and 28 with their respectivelinear and angular heat pipe elements S and y, however, did notestablish any definite trend of movement during the same period of timeand the heat pipes definitely developed a full jacket of frozen soilaround their poles from the ground surface to the permafrost. Itappeared that this jacket is strong enough to prevent any future upwardheave.

Also, the helical heat pipe element y definitely cooled the ground morerapidly than the straight heat pipe element S and created a larger frostjacket around its pole 28 but this additional freezing (above thatoffered by the straight heat pipe element) did not appear necessary toobtain an adequate frost anchor effective the year round. One linearelement S appears to be adequate to anchor its pole 26 having a diameterof approximately l2 inches. For substantially larger diameter poles, twoor more linear elements can be attached equiangularly spacedcircumferentially about such poles. Alternatively, a single angularelement y can be used instead on very large diameterpoles.

FIG. 2 is a front elevational view, shown partially in section and infragments, of the linear heat pipe element S which is normally attachedto the wooden utility pole 26 (FIG. 1). The heat pipe element Sgenerally includes a lower embedded portion 36,'a central connecting teeportion 38, and an upper heat exchanger (radiator) portion 40. The lowerportion 36 is preferably fabricated largely of a tubular (aluminum)extrusion 42 having a central bulbous tube 44 and side flanges or fins46a and 46b. The lower portion 36 is, for example, about 96 inches longand can be conveniently fastened to the pole 26 by nails 42' and washers44 located near the ends of flanges 46a and 46b, and at spacings ofapproximately 12 inches between the ends. The tube 44 has a circularinner diameter nominally of onehalf inch, and is suitably sealed andcovered by a cap 48 at its lower end. With an aluminum extrusion 42,selection and use of a suitable means of corrosion protection such asgalvanic protection, for example, the sacrificial washers 44', orsurface coating protection (organic film or chemical conversion film) isnormally required. A conventional wall screen (wire mesh) wick is notused in the heat pipe element S although such means may be preferablyused in the lower embedded portion 36 when it is very long (in oneinstance, 40 feet, for example). i

FIG. 3 is a fragmentary sectional view of the lower end of the lowerportion 36 of the linear heat pipe element S as taken along the line 3-3indicated in FIG. 2. A standard pinch-off end plug 50 is welded to thelower end of the tube 44. The heat pipe element S can be suitably loadedwith a working fluid such as ammonia through the end plug 50, and thenclosed by pinchoff and seal welding. Approximately 48 grams of ammoniais used, for example, in this illustrative embodiment. The end plug 50is covered by cap 48 which can be secured by epoxy cement to the lowerend of the extrusion 42. Of course, any other suitable form of protective cover for the pinch-off and weld can be used.

FIG. 4 is a side elevational view of the central connecting tee portion38 of the linear heat pipe element S as taken along the line 44indicated in FIG. 2. Referring to both FIGS. 2 and 4, it can be seenthat the upper end of the tube 44 of extrusion 42 is joined to the lowerend of the upper heat exchanger portion 40 by the central portion 38.This central portion 38 includes a tee 52, a lower tube 54, and left andright upper tubes 56 and 58. The ends of the lower tube 54 extendapproximately one-half inch into the upper end of tube 44 and lowerpassageway of tee 52, respectively, and are welded thereto. Similarly,the upper left and right tubes 56 and 58 connect the left tee 52respectively to the lower ends of adapter plugs 60 and 62 mounted inleft and right holes of a bottom support strap 64 as shown in FIG. 2.The upper ends of the hollow adapter plugs 60 and 62 are weldedrespectively to the lower tubular ends of passive radiators 66 and 68 ofthe upper heat exchanger portion 40. While two radiators 66 and 68 havebeen shown, only one or more than two radiators can be appropriatelyused.

FIG. 5 is a cross sectional view of the radiators 66 and 68 of the upperportion 40, astaken along the line 5-5 indicated in FIG. 2. Referringjointly to FIGS. 2 and 5, it can be seen that each of the radiators66and 68 includes'a central tubular body 70 and a plurality of radialfins 72. The fins 72 are circumferentially spaced equiangularly andprotrude a slightdistance (0.15 inch, for example) radially into thetubular body 70 as indicated in FIG. 5. Two of the fins 72; of eachradiator 66 and 68 are welded at their ends to channel members 74 whichare, in turn, fastened to the utility pole 26 (FIG. 1) by lag screws 76and washers 78. The upper end of the tubular body 70 of each of theradiators 66 and 68 is closed by a solid end plug 80 and sealed bywelding. The upper ends of the plugs 80 of the radiators 66 and 68 arerespectively mounted in left and 'right holes of a top support strap 82as shown in FIG. 2. The tubular body 70 is approximately 1 inch indiameter, and the fins 72 are approximately 2 inches wide and 72 incheslong, for example. Obviously, other techniques of attaching theradiators to the pole for support can be used, especially when only oneradiator is employed.

FIG. 6 is a front elevational view, fragmentarily shown, of the angular(helical) heat pipe element y which is normally attached to the woodenutility pole 28 (FIG. I). The heat pipe element y generally includes alower embedded portion 84, a central connecting joint and tee portion86, and an upper heat exchanger (radiator) portion 88. The lower portion84 is fabri-' cated largely of a tubular (aluminum) extrusion having acentral bulbous tube 92 and side flanges or fins 94a and 94b. The tube92 protrudes radially inwards from the flanges 94a and 94b, and theinner diameter of each coil is approximately 12.50 inches, to accommodate a utility pole 12 inches in diameter. The lower portion 84 canbe, for example, about 72 to 96 inches long between the ends of thecoiled section, with six equally spaced coils or a nominal 12 to 16inches lead per coil. The deeper that the pole 28 and its element y areembedded in the ground, the less can be the number of coils since adeeper embedded length tends to offset the lifting of the pole.

The lower portion 84 can be conveniently fastened to the pole 28 bynails 96 and washers 98 located near the ends of the coiled sectionalong the flanges 94a and 94b, and at spacings of approximately 12inches along the longitudinal length thereof. The-lower end of theextrusion 90 of the lower portion 84 is sealed and capped in the samemanner as in the linear heat pipe element S. The tee 100 and everythingabove it, including the heat exchanger portion 88 and its left and rightradiators 102 and 104, can be identical to the tee 52 and heat exchangerportion 40 and its radiators 66 and 68 of the linear heat pipe elementS. The central portion 86 of the angular heat pipe element y includes anoverlapping joint 106 which is not used in the central portion 38 of thelinear heat pipe element S. It is noted, however, that a similaroverlapping joint 106a (indiand right passageways of the cated inphantom lines in FIG. 4) can be readily incorporated and used in thelinear heat pipe element S, if desired or required.

FIG. 7 is a side elevational view of the central portion 86 of theangular heat pipe element y, as taken along the line 7-7 indicated inFIG. 6. Referring to both FIGS. 6 and 7, it can be seen that the angularheat pipe element y is essentially a two-part assembly of a separateupper heat pipe section 108 and a separate lower heat pipe section 110which are thermally joined or connected together by the overlappingjoint 106. Thus, the upper heat pipe section can be readily separatedand detached from the lower heat pipe section, so that it can bereplaced when damaged without having to dig up the entire pole 28 andreplacing an entire heat pipe element because of damage only to theupper radiator portion thereof. The heat removal rate with the twopartassembly, as compared to a similar one-part assembly, is about 12percent less than the latter.

FIG. 8 is a cross sectional view of the central portion 86 of theangular heat pipe element y, as taken along the line 88 indicated inFIG. 7. Referring jointly to FIGS. 7 and 8, it can be seen that theflanges 94a and 94b of each tubular extrusion 90 of the upper and lowerheat pipe sections 108 and 110 are fastened directly together by bolts112 spaced along the length of the overlapping joint 106. A layer 114 ofthermal paste (such as Dow Corning DC-340) can be used between thecontiguous faces of the joined sections 108 and 110 to facilitate heattransfer between the sections. The length of the overlapping joint is,for example, approximately two feet. The lower end of the upper heatpipe section 108 and the upper end of the lower heat pipe section 110are each closed by a pinch-off end plug 116. Ground level can be at afew inches or more below the end plug 116 of the upper heat pipe section108.

FIG. 9 is a front elevational view, shown partially broken away, of astructural support assembly 118 wherein a heat pipe element isintegrally combined with and constructed to serve simultaneously as asupport structure. The assembly 118 includes a closed, elongated,tubular container 120 having a charge of a suitable working fluid (asmall amount ofliquid and remainder vapor) 122, a helical wall fin 124protruding radially inwards a short distance from the internal surfaceof the tubular container, and a heat exchanger (ambient air radiator)126 suitably coupled or integrally incorporated with the upper portionof the tubular container. The assembly 118 further includes a structuralattachment means 128 located normally above radiator 126 although it canin certain applications be located on or below the radiator, and a layer130 of thermal insulation applied in the annual freezethaw ground regionor layer 132 (largely the tundra) about the tubular container 120.

FIG. is a cross sectional view ofa lower part of the support assembly118 as taken along the line l0l0 indicated in FIG. 9. This lower part ofthe assembly 118 includes the lower portion of the tubular container 120with its helical wall fin 124, and is embedded in permafrost 134. FromFIGS. 9 and 10, it can be seen that as the condensate runs down thecontainer 120 wall, the helical wall fin 124 ensures that the wall iswetted all the way around and down. The fin 124 can be a narrow striphelical coil insert, a small diameter spring wire insert or a finehelical screw thread tapped in the tubular container wall, for example,each with a suitable pitch (which can be variable along the containerlength) between turns. Alternatively, a conventional wall screen (wiremesh) wick can be provided on the circumferential wall surfaces of thetubular container 120. It is noted that a helical wall fin or wallscreen wick is not used in the linear or angular heat pipe elements Sand y although such means can be used and may be desirable under certainconditions.

FIG. 11 is a cross sectional view of an upper part of the supportassembly 118 as taken along the line ll-l1 indicated in FIG. 9. It canbe seen that the heat exchanger 126 is a passive radiator including aplurality of vertical fins 136 which extend radially from the upperportion of the tubular container and are equiangularly spacedcircumferentially thereabout. Heat transfer is by way of the surfaces ofthe fins 136 to the ambient air. The tubular container 120 contains asuitable working fluid 122 (such as ammonia) which normally exists as asmall quantity of liquid at the bottom end of the container, withsaturated vapor filling the remainder thereof. This heat pipe device ishighly effective, and the heat transfer process is fully operationalwith temperature drops of less than 1 F in the working fluid 122.

Anytime that the (ambient air) radiator region of the tubular container120 becomes slightly (less than 1 F) cooler than the lower portion ofthe container, some saturated vapor will condense in the radiatorregion, give up its latent heat and then return by gravity down the wallof the container to its lower end. The condensation of fluid 122 in theupper portion of the tubular container 120 tends to decrease thepressure in the container, causing more vapor to flow up it and causingsome evaporation of liquid in the lower embedded portion of thecontainer. The latent heat of evaporation is thus transported from theunderground (embedded) region to the exposed (radiator) region by thisvery efficient refluxing process.

The process of evaporation is, of course, enhanced by the helical wallfin 124 condensate spreader. The complete underground (embedded)container portion acts to remove heat from the surrounding permafrost,and the heat is removed first and most rapidly from wherever thecontainer temperature exceeds the ambient air temperature. That is, heatis removed most rapidly from the warmest part of the undergroundcontainer portion and the device does not depend upon the entireembedded region being warmer than the ambient air before heattransportation begins.

The tubular container 120 is filled mostly with vapor and is, therefore,very light in weight for ease of handling and installation. Undesirableheat conduction downwards is nearly insignificant during warm" weatherfor the structural support assembly l18'because the downward heatconduction (thermal conductivity) in the vapor is very low and theavailable metal cross section is small. The downward heat conduction ismuch greater, for example, in a thermo-valve device. The supportassembly 118 (heat pipe element) can also function efficiently in nearlya horizontal position for stabilization or support of structure onrelatively steep grades whereas a thermo-valve device is very ineffcientor cannot function in such position or orientation.

The structural support assembly 118 need be constructed only heavy andsturdy enough to support the intended structure. Large diameters andthick walls for the tubular container 120 are not required for thenecessary heat transfer function. The support assembly 118 can be usedto support pipelines, railway trusses, buildings, etc. in the arcticregions. Of course, the support assembly 118 need not be confined to theconfiguration shown, and can be suitably combined into anarchitecturaldesign of a building or other structure so as not to beapparent. A number of different working fluids can be individually usedefficiently in the support assembly 118. Thus, the materials ofconstruction of the tubular container 120 can be readily selected tomeet various soil conditions because a variety of working fluids areavailableto provide one which is compatible with any chosen tubularcontainer material.

While certain exemplary embodiments of this invention have beendescribed above and shown in the accompanying drawings, it is to beunderstood that such embodiments are merely illustrative of, and notrestrictive on, the broad invention and that I do not desire to belimited in my invention to the details of construction or arrangementsshown and described, for obvious modifications may occur to personsskilled in the art.

I claim:

'1. For use in ground areas subject to an annual freeze-thaw cycle, astructural support assembly comprising:

a support structure for installation in generally frozen soil, saidsupport structure including a pole structure;

a heat pipe element including a tubular container having a lower andanupper portion, a charge of working fluid in said container, and a heatexchanger coupled to said upper portion of said container, said workingfluid normally existing as a small quantity of liquid in said containerwith saturated vapor filling the remainder thereof, said heat pipeelement being of a configuration and disposition complementary to saidsupport structure and disposed externally thereof, the outer surface ofsaid heat pipe element having an extended heat transfer surfacethroughout substantially the full length of the lower portion of saidtubular container, said lower portion of said container being of agenerally linear configuration, and the lower portions of said supportstructure and said heat pipe element being directly installed in saidfrozen soil whereby said soil adjacent thereto is stabilized in itsfrozen condition throughout the year by said heat pipe element; and

means for attaching said element to said pole structure.

2. The invention as defined in claim 1 wherein said heat pipe elementincludes a two-part assembly comprising a separate lower embeddedsection including said lower container portion, a separate upperradiator section including said upper container portion, and means forcoupling said lower and upper sections in a good heat transferconnection, said lower and upper container portions having respectivecharges of said working fluid therein.

3. The invention as defined in claim 2 wherein said coupling meansincludes an overlapping joint comprising contiguous corresponding flangefaces connecting said lower and upper sections together, and a thermalsubstance provided between the contiguous flange faces of saidoverlapping joint to facilitate heat'transfer therebetween.

4. For use in ground areas subject to an annual freeze-thaw cycle, astructural support assembly comprising:

a support structure for installation in generally frozen soil, saidsupport structure including a pole-like member; and heat pipe elementincluding a tubular container having a charge of working fluid thereinand a heat exchanger coupled to the upper portion of said container,said working fluid normally existing as a small quantity of liquid insaid container with saturated vapor filling the remainder thereof, saidheat pipe element being of a configuration and disposition complementaryto said support structure, the outer surface of said heat pipe elementhaving an extended heat transfer surface throughout substantially thefull length of the lower portion of said tubular container, said lowerportion of said container being of a generally linear configuration, thelower portions of said container and said pole-like member beingcombinationally installed in said frozen soil, and said lower portion ofsaid container being disposed at least adjacent and generally parallelto a surface of said lower portion of said polelike member whereby saidsoil adjacent thereto is stabilized in its frozen condition throughoutthe year by said heat pipe element.

5. The invention as defined in claim 4 further comprising means forattaching said element to said polelike member.

6. In a structural support assembly for use in ground areas subject toan annual freeze-thaw cycle, the combination with a support structurefor installation in generally frozen soil, said supportstructureincluding a pole-like member, of:

a heat pipe element including a tubular container ,having a charge ofworking fluid therein and a heat exchanger coupled to the upper portionof said container, said working fluid normally existing as a smallquantity of liquid in said container with saturated vapor filling theremainder thereof, said heat pipe element being of a configuration anddisposition complementary to said support structure, the outer surfaceof said heat pipe element having an extended heat transfer surfacethroughout substantially the full length of the lower portion of saidtubular container, said lower portion of said container being of agenerally linear configuration, the lower portions of said container andsaid pole-like .member being adapted to be combinationally installed insaid frozen soil, and said lower portion of said container beingdisposed at least adjacent and generally parallel to a surface of saidlower portion of said pole-like member whereby said soil adjacentthereto is stabilized in its frozen condition throughout the year bysaid heat pipe element.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION PATENT NO.3,840,068

DATED 1 October 8, l97 l |NVENT0R(5) 3 Elmer Dale Waters It is certifiedthat error appears in the above-identified patent and that said LettersPatent are hereby corrected as shown below;

Front page, left column, in the "Notice" section, the date "Jan. 29,1990" should read Jan. 29, l99l.

Column 1, line 39, the word "overaly" should read overlay.

Signed and Scaled this I second Day Of March 1976 [SEAL] Attest:

RUTH C. MASON C. MARSHALL DANN Arresting Officer Commissioner of Patentsand Trademarks

1. For use in ground areas subject to an annual freeze-thaw cycle, a structural support assembly comprising: a support structure for installation in generally frozen soil, said support structure including a pole structure; a heat pipe element including a tubular container having a lower and an upper portion, a charge of working fluid in said container, and a heat exchanger coupled to said upper portion of said container, said working fluid normally existing as a small quantity of liquid in said container with saturated vapor filling the remainder thereof, said heat pipe element being of a configuration and disposition complementary to said support structure and disposed externally thereof, the outer surface of said heat pipe element having an extended heat transfer surface throughout substantially the full length of the lower portion of said tubular container, said lower portion of said container being of a generally linear configuration, and the lower portions of said support structure and said heat pipe element being directly installed in said frozen soil whereby said soil adjacent thereto is stabilized in its frozen condition throughout the year by said heat pipe element; and means for attaching said element to said pole structure.
 2. The invention as defined in claim 1 wherein said heat pipe element includes a two-part assembly comprising a separate lower embedded section including said lower container portion, a separate upper rAdiator section including said upper container portion, and means for coupling said lower and upper sections in a good heat transfer connection, said lower and upper container portions having respective charges of said working fluid therein.
 3. The invention as defined in claim 2 wherein said coupling means includes an overlapping joint comprising contiguous corresponding flange faces connecting said lower and upper sections together, and a thermal substance provided between the contiguous flange faces of said overlapping joint to facilitate heat transfer therebetween.
 4. For use in ground areas subject to an annual freeze-thaw cycle, a structural support assembly comprising: a support structure for installation in generally frozen soil, said support structure including a pole-like member; and a heat pipe element including a tubular container having a charge of working fluid therein and a heat exchanger coupled to the upper portion of said container, said working fluid normally existing as a small quantity of liquid in said container with saturated vapor filling the remainder thereof, said heat pipe element being of a configuration and disposition complementary to said support structure, the outer surface of said heat pipe element having an extended heat transfer surface throughout substantially the full length of the lower portion of said tubular container, said lower portion of said container being of a generally linear configuration, the lower portions of said container and said pole-like member being combinationally installed in said frozen soil, and said lower portion of said container being disposed at least adjacent and generally parallel to a surface of said lower portion of said pole-like member whereby said soil adjacent thereto is stabilized in its frozen condition throughout the year by said heat pipe element.
 5. The invention as defined in claim 4 further comprising means for attaching said element to said pole-like member.
 6. In a structural support assembly for use in ground areas subject to an annual freeze-thaw cycle, the combination with a support structure for installation in generally frozen soil, said support structure including a pole-like member, of: a heat pipe element including a tubular container having a charge of working fluid therein and a heat exchanger coupled to the upper portion of said container, said working fluid normally existing as a small quantity of liquid in said container with saturated vapor filling the remainder thereof, said heat pipe element being of a configuration and disposition complementary to said support structure, the outer surface of said heat pipe element having an extended heat transfer surface throughout substantially the full length of the lower portion of said tubular container, said lower portion of said container being of a generally linear configuration, the lower portions of said container and said pole-like member being adapted to be combinationally installed in said frozen soil, and said lower portion of said container being disposed at least adjacent and generally parallel to a surface of said lower portion of said pole-like member whereby said soil adjacent thereto is stabilized in its frozen condition throughout the year by said heat pipe element. 